Stabilized reaction products of rubbery polymers with inorganic acidifying compounds



Patented Oct. 6, 1953 I,

UNITED STATES PATENT OFFICE STABILIZED REACTION PRODUCTS F RUBBERY POLYMERS WITH INORGANIC ACIDIFYINGYCOMPOUNDS Johan Michael Goppel, Gottfried Ernst Rumscheidt, and Johannes Thomas Hackmann, Amsterdam, Netherlands, assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application April 26, 1949, Serial No. 89,801. In The Netherlands May 18, 1948 19'Claims. (Cl. 117-138.8)

This invention is directed to a process for the the vinyl esters and various unsaturated aldestabilization of products formed on reacting in hydes, ketones and'ethers, e. g., acrolein, methyl organic acidifying compounds with rubbery polyisopropenyl ketone,and vinyl ethyl ether. The

mere comprising high molecular weight, polyabove-defined, polyunsaturated, high molecular unsaturated compounds. The invention also reweight compounds, including both natural and lates to the resulting stabilized reaction products. synthetic rubbers, may properly be termed high The term high molecular weight, polyunsat-- molecular weight polymers of diene-hydrocarurated compound," as employed herein, embons, or preferably, "rubbery polymers of at braces those compounds having a molecular least one compound selected from the group Weight of at least 5,000 and which contain a consisting of the conjugated diolefines and chloplurality of unsaturated linkages in the moleroprene. cule. These compounds are either polymers of As employed herein, the term inorganic acidiorganic compounds containing a plurality of unfying compound embracesthe various inorganic saturated linkages in the molecule, or arecoacids and acid anhydrides wherein the acidpolymers of such multiple-unsaturated com-' 5 forming element (as sulfur, nitrogen or phospounds with other unsaturated organic comphorus, for example), if possessing several valpounds of one type or another. The term inencies, is present, in a, valency other than the clucles the various natural rubbers such as latex, highest thereof. Preferred acidifying comcrepe, sheet, caoutchouc, gutta percha, balata, pounds are the acid anhydrides, sulfur dioxide, and cyclo rubbers, as well as unsaturated syno phosphorus trioxide and nitrous trioxide, as well thetic rubbers. Representative synthetic polyas the acids formed from these anhydrides. mers of high molecular weight are the polymer- Other useful acidifying compounds are hydrogen ization products of butadiene and those of its sulfide, hydrochloric acid, hydrobromic acid, hyhomologues and derivatives, as, for example,- droiodic acid, and hydrofluoric acid. The term methyl butadiene polymers, dimethyl butadiene does not include such compounds as sulfur tripolymers, pentadiene polymers, and chloroprene oxide,'phosphorus pentoxide, nitrogen pentoxide, polymers (neoprene syntheticrubber) Repreor theircorrespondingacids, for in all these sentative copolymers of high molecular weight compounds the acid-forming element, which is which come within the termare those formed here either sulfur, phosphorus or nitrogen, is from butadiene, its homologues and derivatives, 0 present in 'thehighest of several possible valenwith other unsaturated organic compounds. cies. Oi-the various acidifying compounds set Among the latter are the acetylenes, as vinyl fcrthherein, thefmost preferred compound for acetylene, the olefins, as isobutylene which coemployment in the present invention 'is sulfur polymerizes with butadiene to form butyl' syndioxide. thetic rubber; the vinyls, as vinyl chloride, It is known that the high molecularweig'ht acrylic acid, acrylonitrile (which polymerizes polyunsaturated compounds lend themselves well with butadiene to form the synthetic rubber to the production of various shapes, including- Buna-N), methacrylic acid, and styrene, the" those of a continuous, non-supported nature, as latter compound polymerizing withbutadiene' to filaments, rods, strips, sheets, and the like. 'Furform the syntheti rubber Buna S; as well as 40, thermore, it is known that the properties of peroxide such as decalin Activation methods of this such shapes may be improved by reacting the unsaturated, high molecular weight compound with one or more of the inorganic acidifying compounds mentioned above, particularly sulfur dioxide. The exact nature of this reaction is not clearly understood, though it is evident that a quantity of the acidifying ingredient is taken up in one form or another by the high molecular weight reactant. The extent of this reaction is normally measured by, and expressed in terms of, the amount of acid-forming element (sulfur, phosphorus or nitrogen, for example) present in the resulting reaction product.

It has also been possible to improve the nature of the foregoing reaction products by incorporating therein, normally prior to the reaction with sulfur dioxide or other acidifying ingredient, a quantity of a low molecular weight, unsaturated compound. The resulting reaction product has a number of advantages, chief among which is a greatly improved acceptance for all the commonly employed dyestuifs. saturated compounds which may be employed in this manner, all of which have a molecular weight of below 5,000 are alkadienes such as butadiene and 1,5-hexadiene, and alkenyl compounds acetate, allyl capronate, allyl isothiocyanate, allyl oleate, and more especially, diallyl compounds such as diallyl phthalate and diallyl adipate. The method by which unsaturated reactants of both high and low molecular weight Representative unvariety of ways, but chiefly in a sharp falling off in tensile strength and in the degree of permissible stretch prior to rupture. In many instances undesirable color changes also ensue. These various changes are greatly speeded up as the objects under consideration are heated, particularly above 100 C., or are exposed to ultraviolet light. It has been observed that the deterioration in physical properties is attended by a loss of sulfur dioxide or equivalent acid constituent from the reaction product, a loss which is generally proportional to the aforementioned deterioration. Accordingly, the rapidity with which a given product loses its acid constituent may also be taken as a measure of its stability,

i. e., its resistance to deterioration with age, heating, and/or exposure to ultra-violet or other light rays. 7

It is an object of the present invention to provide a method for obtaining stable products of the type formed on the reaction of high molecular Iweight, polyunsaturated compounds with inorsuch as allyl alcohol, allyl chloride, allyl are utilized in forming reaction products with acidifying compounds forms the subject of copending application, Serial No. 15,048, filed March 15, 1948, and reference is hereby made to said application for a more complete description of the invention there disclosed.

It should be noted that while the high molecular weight, polyunsaturated compounds, or mixtures of both high as well as low molecular weight unsaturated compounds, may bereacted with the acidifying compound without prior modification of either reactant, improved results are obtained when are first activated by treatment with a hydrohydroperoxide, or tetralin hydroperoxide. nature are disclosedv in copending applications, Serial Nos. 760,924, filed July 14, 1947, and 788,312, filed November 26, 1947, to which applications reference is here made. The peroxide treatmentis also disclosed in copending application Serial No. 15,048, referred to above, as said activation treatment relates to mixtures of high and low molecular weight unsaturated reactants.

While the reaction products discussed above have proven well adapted for many uses, they have provzn particularly useful when formed into filaments of the type which can be woven into textiles, either alone or in conjunction with fibers of other materials. Thus, filaments produced by spinning a, peroxide-activated rubber solution have a high elementary denier, with good tensile strength, arelatively high degree of elongation prior to rupture, and good flexibility and other characteristics making for ease of working and handling. In view of these many favorable qualities, it has been highly disappointing to realize that ,even in the case of the best reaction products hitherto obtainable, deterioration of the filament or other shape with age, heating and/or exposure to ultra-violet light is unduly rapid. This deterioration is manifest d a the unsaturated compounds ganic acidifying compounds, or of both such compounds with low molecular Weight, unsaturated compounds.

A more particular object is to provide filaments and like continuous, non-supported shapes composed of the reaction products discussed above, yet which are highly stable and are characterized by a continued high tensile strength and degree of stretch prior to rupture, as well as by a relatively small loss of acidifying compound, when said filaments or shapes are aged, heated and/or exposed to light rays. a

The nature of still other objects will become apparent from the following description of the invention.

It has been discovered that excellent resistance to deterioration with age, heat and/or exposure to ultra-violet light may be imparted to objects composed of the product formed on reacting high molecular weight, polyunsaturated compounds with inorganic acidifying compounds and either with or without a low molecular weight unsaturated compound, by incorporating in said objects one or more compounds selected from the heptadecenylamine, diisopropylamine, dioctyl- V amine, dioctadecylamine, 'N-octyl-heptadecylinto a sulfur dioxide-containing coagulating bath amine, triethylamine, N-propyl-diethylamine, N-

alkyl-diethylamine and undecenylamine; aralkyl monoamines, such as benzylamine, phenethylamine; .carbocyclic aromatic amines in which the amino nitrogen atom is directly attached to the aryl nucleus, and in which the amino nitrogen atom is unsubstituted with other than such aryl groups, examples of 1 this group being o-toluidine, p-toluidine, cumidine, alpha-naphthylamine, p-phenylenediamine,

p-diaminobiphenyl, N-cetylaniline, N-phenylbeta-naphthylamine, triaminobenzene, diphenylamine, Nmethyl-N-isoamyl-aniline, N-ethyl-N- octylaniline,ethyl-N-hexylaniline and triphenylamine,. cyclohexylamine, cyclopentylamine, 1,2-

propanediamine, 1,4; naphthalenediamine, 4-

" benzylamine, N-ethylmethylcyclohexylamine, 4,4 diaminodiphenylethane; and-di*--(p"- amylphenyliamine: Also included by theterm amine are the' various polar" substituted compounds such as amino al cobalt and aminoacids as well' as the N-halo amines: Representative" substituted amino com pounds are triethanolamineg dibut'ylethanol amine; p a-mihophenolg' N;N-"-dichlbroquinone-- diimii'le; beta-aminopropionic' acid} alpha-aminoca-prylic' acid, allylb'eta-aminooapronate, diallyl" 4 amin-132-benzenedicarboxylate and ethyl p-- amihobenzoate. In: general, aprefer-red class-of amines ismade up of those compounds having at least one primary amine (NH2-) group.

A more preferredclassof aminespoming withinthe foregoing class i's tliat comprising heterocycllc compounds having onlycarbon and' nit'ro-- gen-atoms in the ring, representative compounds of" this; preferred class being hexamethylene tetramine, melamine, phenyl' melamine, 2'-(2- methyldodecylypyr-idine; (inethyl -2-dodecyl)--2-- pyridine, 8 -oxy-qui'noli'ne and pii'enylin'dole: Of these heterocyclic' amines it is mostpreferred to" use at least one compound selected from the group consisting of hex-amethylenetetramine and melamine, the same being used alone; in conjunction with one another, or with other amine compounds.

It also forms a feature of the present invention to stabilize the above-described reaction products with both an amine of the type described in the preceding paragraphs together with an aminehaving the general formula:

wherein. X is oxygen, sulfur-4 or the. imine (NI-I group and. R1, Reand; Re represent hydrogen atoms, hydrocarbon radicals or polar-substituted.- hydrocarbonradicals. Compounds, of this; class; representative: members of which. are urea, thiourea, quanidine, N, l .T-- and N-Nf-diphenyl; ureaNN-and- N ,l .l -dipheny1 thiourea and N,N+ and N,1 T '-dipheny1 quanidine; are disclosed inour copending application, Serial- No. 37 056, filed J uly, 3,,198, as useful stabilizersrfoir the reaction. products discussed! above When amines (if-the: foregoing. types: are: employed in conjunction! with one another in. sulfur. diox-ide rubbeny polymer reaction products, thereis observed not only an improved stabilityinthe treated-reactionL products. but. also. an improvement. in the; ability of. the. latter to retain their improved. stabilityeven after repeated washings in hot; soap solu tions; This. isi particularly the case with combinations ofthiourea. and/or urea withmelamine and/or hexamethylene" tetramine.

The term aminesaltsf includes.- compounds: of the type formed by reacting an: amine of the; type containing buta single amino nitrogen atomv attached to any given. carbon atom not; forming,

a part of a ring with a mineral acid, for: example, as well as quarternary salts. of'the. type formed by reacting a, tertiary-amine. of. the foregoing type with an alkyl, halide, for. example. Representative compounds fallin into this class are aniline hydrochloride, dimethyldiethylammonium iodide, tetramethylammonium chloride, trimethylam-inehydrochloride, undecyl:

amine hydrochloride, .N-cetylan-iline. hydro chloride cetylamine hydrochloride, cetylpyri dinium bromide, cetyltrimethylainmonium bro.-

mide cetylpyridimium chloride and diethyloctadecyloxymethylammonium chloride;

- Thepresent invention' also contemplates using one or; more-compoundsfrom the-aforedesigg ated I class consisting-- of amines and; amine salt together-with one" or more amides-- in order toim; prove the-stability; of the above described" reaction-products: herein; includes such: compounds; as; acetamide, stearic ac-id amide; benzamide and acetanilide; forexample. I

The stabilizer chosen; which, as noted'a-bove; may be one or-a mixture of severalcompounds; can' beintroduced into the reaction product: in one orm'ore-o-fa number-of d-ifferentways; Thus;

' for example, the stabili 'zern ay -beaddedto the;

alkaline stabilizers are employed; the preferred manner of addingthe stabilizer is to bring a solution thereof intocon-tact formed reaction product; preferably when the; latter-is still inthe-swollen condition due to its manner of production in the; coagulating bath and/or; as aresult of subsequent washing steps. Thus, filaments produced by;- spinning a. solution, of peroxide-activated rubber int o an ethanol-3 water-suliur dioxidecoaeulatinebat i av th r f r. beimmersed in. a. solution. of s b liz.er. s.. examethylene tetramin int water; or. than l for. example, and. left, therein for desi edr p riod of; time. other ppropr at sol ents e:

; acetone}, propanoli, butanol; nd: me hyl: thyl: k

tone; Q13: being withdrawn'firom the, stabilizer solution, the filaments; may. then be washed in the conventional manner, as withalcohol, water, dilute caustic or other-liquid, stretched, dyed, or otherwise treated; following which they may be dried and used. If desired, one or more of such Washing, stretching and/0r dyeing steps may intervene between the actualiprecipitation of the filaments in the coagulating bath and, their imm rsion in the. stabili er s lution. the filaments preterably remaining in he sw l n conditions during, all, said. processing st ps. olt mati ve m. he. filaments may be. treated i he dr ed. (11

60. swollen) condition wi h a. soluti f, the d ir d of stabilizers or with an tains the stabilizers stabilizin compound. pref rab y in a. s l nt, such as benzene, ethy al oheL, acetone: r ethyl acetate which a s o well: he: filamen th u h no filament: swelling solvents such as: water may be employed in many: cases. The stabilizers. may also be applied on or inv the material to be sta bili-zedotherwise than impregnation. Thus, the material may be contacted with dispersions atmosphere which constate. In the latter case a solution of the stab}. lizer may be atomized, i f .desi red. M

The oncentration" f stabilizer to emp o whether the samehbe'added t tlie;

with the alreadyin the. vaporous or atomized materials, or is applied as a solution to the already formed reaction product, is not critical. Thus, good results are obtained with solutions containing from about 0.1 to 20% by weight of a stabilizer, and some improvement can be effected even when using smaller quantities than 0.1%, particularly when more than one stabilizer be employed. Preferably, however, the concentration of stabilizer should be at least 0.5%,

somewhat shortened. Another factor is theease with which the reaction product is able to take up the stabilizer solution; thus, freshly formed, undried products (e. g., swollen filaments) are considerably more receptive to the stabilizer solution than are objects which have already been dried and now must take up fresh quantities of solvent along with the dissolved stabilizer. In general, immersion periods of from 1 to 30 minutes are satisfactory with swollen filaments, though soaking'periods of one or more hours are desirable when treating dried filaments. In all cases, extension of the soaking time is in no way harmful and in many cases proves of considerable benefit. Where the stabilizer is added to the unreacted solution of rubber or sulfur dioxide, for example, no modification need be made in the normal process by which said compounds are reacted.

of more importance than the duration of the treatment with stabilizer solution is the temperature thereof. It forms a feature of the present invention that improved results are obtained by employing a heated stabilizer solution, by which term is meant a solution having a temperature of 50 C. or above, and preferably between 50 and 150 C. The use of such heated solutions serves in a measure to fix the stabilizer in the reaction product, thereby increasing its resistance to removal during ageing, or as a result of subsequent washing or other treating steps. 7

Still further improved results, notably as regards increased stability and resistance against age deterioration following soap washing and/or alkali-treating steps, are achieved by subjecting reaction products already impregnated with stabilizer compound to a treatment involving heating in a gaseous environment such as. air or nitrogen. The temperatures employed in this heating step may range from about 50 to 250 C., though temperatures of from about 80 to 150 C. are preferred. Effective treatments carried out in the latter temperature range normally take from /2 to 4 or more hours, the relatively higher temperature permitting effective use of the shorter treating intervals. This dry heating step may be practiced with beneficial results no matter whether the impregnation treatment referred to in the preceding paragraph be conducted at elevated temperatures or not, though as a general rule the one heating treatment re-enforces the other. r

It has also been found that improved results as'regards fixation of stabilizer may be obtained decenylamine or diallyl 4amino-l,2-benzenedicarboxylate, which contain one or more alkenyl or other unsaturated, aliphatic groups. Such unsaturated stabilizing compounds are preferably introduced into a solution of rubber or other high molecular weight reactant prior to its reaction with the acidic compound if the full effect of the stabilization treatment is to be obtained, for it seems quite probable that under these circumstances the stabilizer enters into, and chemically forms a part of, the final reaction product.

Still a third way of improving the bond between the reaction product and the stabilizer is to treat the already stabilized product with an aldehyde or isocyanate, the stabilizer present in the product reacting with the aldehyde or isocyanate under these circumstances to form condensation or poly-addition compounds, either of which are of such a character as to be washed out of the product only with the greatest difficulty.

The following examples illustrate the present invention in various of its embodiments:

Example I The material to be stabilized was a reaction product of natural rubber with sulfur dioxide in the form of dried filaments with a sulfur content of 22%, which material was produced by spinning a solution of natural rubber and tetralin hydrcperoxide into a sulfur dioxide-containing coagulating bath and thereafter stretching, soaking and drying the filaments. Samples of these dried filaments were soaked in solutions of various stabilizers or combinations of stabilizers for 4 hours, after which they were cursorily rinsed with ethanol and dried in the open air, the concentration and temperature of the various stabilizer solutions. as well as their identity, being indicated in Table I below. Some of the samples were then washed for 4 hours at 60 C. with a 0.4% solution of Marseilles soap,

and in a few cases the soap treatment was re-' peated. The stability of the samples was determined both before and after washing, the stability in each test being determined by measuring the ouantity of S02 liberated per unit of weight of the material upon heating the same for 2 hours at 125 C. in an air current. In the case of the tests reported in Table I below. t is S02 loss is expressed as the percentage of the quantity of S02 liberated per unit of weight in a blank test, 1. e., with like filaments unstabilized but otherwise subjected to the same physical treatment as the stabilized products. The actual quantity of S02 split off from the various blank samples during each 2 hour heating test period varied from about 1.5 to, 3% by weight of the entire sample, this corresponding to a loss in tensile strength of from about 9 to 18%.

Moreover, comparative tests werecarried out on the sample stabilized with the 1% aqueous melamine solution at 55 C, and marked with (x) was still of its original value atthe end of this extended heating period.

. s eeemhee q Stabilizer j conoe'n'i v tration stabilizer 'inpfercent f Sale/int- O None; Heptadecyl amine; a-naphthyl amlne.. p-phenylene diamine cetyl pyridinium chloride hexamethylene tetramine and" melamine.

hexamethyleno tetramlne' and'{ melamine.

hexarnethylene tetramlne tetramine' thiourea. hexamethylene tetram'ine tetrainine iourean hexamethylene tetramine melamine and -thlourea and v and: 4

and hiourea. hexamethylene or hexamethylene urea.

and;

ExampleII The stabilizatiom operation-S summarized; Example I above involved soaking:the dfiedfila; ments for 4-hours in the-desired stabilizer 5611 tioni On repeating-the soaking 'experinients withf freshly prepared, swollen" filaments" it is found that equivalent results as'regardsfreedom' from loss of sulfur dioxide and general' stabilitydnthefi finally: dried filaments are 'obtail'led byisoaliing the filaments in stabilize-r solution's ioi' 4 periods" of :fromTl to minutes? Eil'ample III;

This example illustrates! the? advantagesachieved bysoaking the unstabilized filaments in hot solutions of: the& desiredipstabilizing "com? pounds. Inthis case oneslotof: filaments of "t e kind described in Example' 'l'above wasfimmersed for a period of .14 hours: inta-zl aqueous solution; of melamine maintainedzat'zoi" G. .another 'lotiof the same filaments waslsoaked ima similar' man ner, but withthe melamine:solutionzmaintained at C. Bothlots of 'filaments wverezthen dried? andgiven an accelerated'ageing"testwhereinither filaments were heatedin-air1att125fi'0:for ZIhOlH'Si"? The filaments soaked;at 20 lost 30349;; i-bywveight sulfur dioxide during: I this; test'rwhereawthose r soaked at 55 lost= only-0.28% by-rweightathereof tt,

In another operation; filaments:'ofrtliew'sameo' variety; were stabilizedrbyaimmersiomfori:hour in a 2% solution of-=hexamethylenetetramine'einn" ethanol, the bath tlnaz-onefloaserbeing main tainedat 20 0. andvinrth ther w t' fzag ar 0 being dried and heated .in airhfor zuliours 43,125; 0., those filaments wsoaked .at.v20' lost 0,26%Tby weight sulfur dioxide whereas tljOse'jSdtikdlatQ 78 lost only 0.21%"by,weightlof com und.

This example illustrates the benefits" achieved by heating the stabilized filaments in "gaseous environment, both vv-itharr'd without a @preV'ious heating via the solution of stabilizing compound.

The resiilts given in Table II below showthat filaments. subjected to: such] heat treatment'(s) exhibitia' 'greatly improved stability- (as measured in te'rms'iofr sulfur: dioxide loss) even: after severe washingziniisoa'p solutions} Inmaliingthese tests all t samples excepting: the? blank were first impregnated :by soaking: dried filafnents of the "type desori'bedtrini Examplell withxa 2 solution' of liexamethylen'etetramine" in" ethanol "for" 4 fhours', inftlieonei casea-t20 "(liandIfin th'e other at 78 C. The washingi'treatment' 'refrred" o in the table is one whereby dried, stabilized; pregnate'dfilaments were washed for "4 l'iours at60 C? with a 014% so'ap'so1iitibm" followed" byu ins ng; for 17 hours inf Water at' ZO" The air' heating 1 step referred" to inf thetable' is one whereby the stabiliae di filaments werejlieated'jin fair at F101 for? hourgjeither 'beforeorfafter' the soap washmgtreatmem; asindicttdf 'rnisiinn 1 Percent- By weightofsul--- furdioxide 10st on'heat ing-the fully treated sam ple in air for 2 hours at 125 C.

Test No. I

famin above data/it will be fseen that evert thou h the washing treatment be [sol severe asto nullify "the benefits normany obtained through use of the hot solution of stabilizers (Test No. 3),

Example V The present example again illustrates the benefits achieved by air-heating thestabilized fibers,

the washing in this case being in a 0.1 N solution of sodium hydroxide. Dried filaments similar in kind to those described in Example I above were stabilized by impregnation for 4 hours in a 2% aqueous solution of melamine at 80 C., the blank excepted. One portion of the sostabilized filaments were then heated in air at 125 C. for 2 hours whereas the others were not. All filaments, including the blank, were then immersed in a 0.1 N aqueous solution of NaOH at 20 C. for 4 hours, following which the filaments were washed in water for 48 hours and in ethanol for 24 hours. The filaments were then dried and tested for sulfur dioxide loss occurring during heating at 125 C. for 2 hours. In the case of the blank the sulfur dioxide'loss was 14.5%. Those filaments stabilized with melamine, but not heated in air prefatory to caustic washing lost 3.42% by weight sulfur dioxide. However, the loss was reduced to only 0.3% in the case of the air-heated fibers.

Example VI Synthetic rubber filaments containing approximately 20% sulfur dioxide were produced by spinning a solution of butadiene polymer (molecular weight approximately"50,'0-00) activated with tetralin hydroperoxide into an ethanolwater coagulating bath containing dissolved sulfur dioxide. One lot of these filaments was stabilized by soaking in an ethanol solution containing 0.75% by weight thiourea and 0.75% by weight hexamethylenetetramine at 20 C. for a period of 4 hours whereas the other group was soaked in ethanol only. On drying both sets of filaments it was found that those impregnated with thiourea-hexamethylene dicyandiamide had a resistance against thermal deterioration which was approximately 5 times as great as that of the unstabilized filaments.

The invention claimed is:

1. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing hexamethylenetetramine.

2. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising immersing said product, while it is in a swollen, coagulated state, in a heated solution containing hexamethylenetetramine.

'3. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing hexamethylenetetramine, and thereafter heating the product in a gaseous environment.

4. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen,

coagulated state, with a heated solution containing hexamethylenetetramine, and thereafter heating the impregnated product in a gaseous environment.

5. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing a mixture made up of hexamethylenetetramine and dicyandiamide, r

6. The method of increasing the resistance to deterioration of a product'formed on the reaction of a high molecular weight, synthetic, rubbery butadiene polymer with sulfur dioxide, these being the only reactants, said method comprising impregnating said productjwhile, it is in a swollen, coagulated state, with a solution containing hexamethylenetetramine as stabilizer.

7. The method of increasing the resistance to deterioration of a productiormed on the reaction of a high molecular weight, synthetic, rubbery butadiene polymerwith sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing a mixture of stabilizers containing hexamethylenetetramine, and dicyandiamide.

8. The method of claim 6 wherein the stabilizer-containing reaction product is impregnated with an aldehyde to fix the stabilizer compound in the reaction product.

9. The method of claim 6 wherein the stabilizer-containing reaction product is impregnated with an isocyanate to fix the stabilizer compound in the reaction product.

10. In a method wherein a solution of natural rubber and tetralin hydroperoxide is injected into a coagulating bath containing available sulfur dioxide, these being the only reactants, whereby there is precipitated in the bath a reaction product of the rubber and sulfur dioxide in the form of a continuous, swollen filament which is then withdrawn from the coagulating bath, the step comprising impregnating the still swollen filament with a solution containing hexamethylenetetramine as stabilizer.

, 11. In a method wherein a solution of a rubbery polymer of at least one compound selected from the group consisting of the conjugated diolefins and chloroprene in the presence of a peroxide activating agent is injected into a coagulating bath containing available sulfur dioxide, these being the only reactants, whereby there is precipitated in the bath a reaction product of the rubbery polymer and sulfur dioxide which is. then withdrawn from the coagulating bath, the step comprising impregnating without dissolving the still-swollen reaction product with a solution containing at least one stabilizer compound selected from the group consisting of (1) saturated, unsubstituted aliphatic monoamines; (2.) carbocyclic aromatic amines in which the amino nitrogen atom is directly attached to the aryl nucleus and in which the amino nitrogen atom is unsubstituted with other than such aryl groups; (3) heterocyclic amines having only carbon and nitrogen atoms in the ring; and (4) salts of said amines, in all cases the amines containing but a single nitrogen atom attached to any given carbon atom not forming a part of a ring.

12. A novel stabilized composition of matter comprising a reaction product of a rubbery polymer of at least one compound selected from the group consisting of the conjugated diolefins and chloroprene in the presence of a peroxide activating agent and sulfur dioxide, these being the only reactants, which composition of matter is prepared by impregnating said reaction product, while it is in coagulated state, having a definite form and swollen with solvent, with a solution of at least one stabilizer compound selected from the group consisting of (1) saturated, unsubstituted aliphatic monoamines; (2) carbocyclic aromatic amines in which the amino nitrogen atom is directly attached to the aryl nucleus and in which the amino nitrogen atom is unsubstituted with other than such aryl groups; (3) heterocyclic amines having only carbon and nitrogen atoms in the ring; and (4) salts of said amines, in all cases the amines containing but a single nitrogen atom attached to any given carbon atom not forming a part of a ring, and removing said solvent, said stabilized composition of matter being characterized by a high resistance to deterioration.

13. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing melamine.

14. The method of increasing the resistance to deterioration of a product formed on the reaction of natural rubber with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a heated solution containing melamine, and thereafter heating the impregnated product in a gaseous environment.

15. The method of increasing the resistance to deterioration of the product formed on the reaction of a high molecular weight, synthetic, rubbery butadiene polymer with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing melamine as stabilizer.

16. The method of increasing the resistance to deterioration of the product formed on the reaction of a high molecular weight, synthetic, rubbery butadiene polymer with sulfur dioxide, these being the only reactants, said method comprising impregnating said product, while it is in a swollen, coagulated state, with a solution containing a mixture of melamine and dicyandiamide as stabilizers.

17. In a method wherein a solution of natural rubber and tetralin hydroperoxide is injected into a coagulating bath containing available sulfur dioxide, these being the only reactants, whereby there is precipitated in the bath a reaction product of the rubber and sulfur dioxide in the form of a continuous, swollen filament which is then withdrawn from the coagulating bath, the step comprising impregnating the still-swollen filament with a solution containing melamine as stabilizer.

18. In a method wherein a solution of natural rubber in the presence of a peroxide activating agent is injected into a coagulating bath containing available sulfur dioxide, these being the only reactants, whereby there is precipitated in the bath a reaction product of the rubbery polymer and sulfur dioxide in the form of a continuous swollen filament which is then withdrawn from the coagulating bath, the step comprising impregnating without dissolving the still-swollen filament with a solution containing at least one stabilizer compound selected from the group consisting of (1) saturated, unsubstituted aliphatic monoamines; (2) carbocyclic aromatic amines in which the amino nitrogen atom is directly attached to the aryl nucleus and in which the amino nitrogen atom is unsubstituted with other than such aryl groups; (3) heterocyclic amines having only carbon and nitrogen atoms in the ring; and (4) salts of said amines, in all cases the amines containing but a single nitrogen atom attached to any given carbon atom not forming a part of a ring.

19. A novel stabilized composition of matter comprising a reaction product of natural rubber and sulfur dioxide in the presence of a peroxide activating agent, these being the only reactants, which composition of matter is prepared by impregnating said reaction product, while it is in coagulated state, having a definite form and swollen with solvent, with a solution containing at least one stabilizer compound selected from the group consisting of (1) saturated, unsubstituted aliphatic monoamines; (2) carbocyclic aromatic amines in which the amino nitrogen atom is directly attached to the ary1 nucleus and in which the amino nitrogen atom is unsubstituted with other than such aryl groups; (3) heterocyclic amines having only carbon and nitrogen atoms in the ring; and (4) salts of said amines, in all cases the amines containing but a single nitrogen atom attached to any given carbon atom not forming a part of'a ring, said impregnated reaction product being characterized by a high resistance to deterioration.

J OHAN MICHAEL GOPPEL. GOTTFRIED ERNST RUMSCHEIDT. JOHANNES THOMAS HACKMANN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,302,362 Nelles Nov. 1'7, 1942 2,379,354 Hilton June 26, 1945 2,396,556 Cox Mar. 12, 1946 2,403,960 Stoops July 16, 1946 2,439,610 Morris Apr. 12, 1948 2,469,847 Rumscheidt May 10, 1949 2,511,498 Die Nie June 13, 1950 FOREIGN PATENTS Number Country Date 575,736 Great Britain Mar. 4, 1946 593,036 Great Britain Oct. 7, 1947 

12. A NOVEL STABILIZED COMPOSITION OF MATTER COMPRISING A REACTION PRODUCT OF A RUBBERY POLYMER OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE CONJUGATED DIOLEFINS AND CHLOROPRENE IN THE PRESENCE OF A PEROXIDE ACTIVATING AGENT AND SULFUR DIOXIDE, THESE BEING THE ONLY REACTANTS, WHICH COMPOSITION OF MATTER IS PREPARED BY IMPREGNATING SAID REACTION PRODUCT, WHILE IT IS IN COAGULATED STATE, HAVING A DEFINITE FORM AND SWOLLEN WITH SOLVENT, WITH A SOLUTION OF AT LEAST ONE STABILIZER COMPOUND SELECTED FROM THE GROUP CONSISTING OF (1) SATURATED, UNSUBSTITUTED ALIPHATIC MONOAMINES; (2) CARBOCYCLIC AROMATIC AMINES IN WHICH THE AMINO NITROGEN ATOM IS DIRECTLY ATTACHED TO THE ARYL NUCLEUS AND IN WHICH THE AMINO NITROGEN ATOM IS UNSUBSTITUTED WITH OTHER THAN SUCH ARYL GROUPS; (3) HETEROCYCLIC AMINES HAVING ONLY CARBON AND NITROGEN ATOMS IN THE RING; AND (4) SALTS OF SAID AMINES, IN ALL CASES THE AMINES CONTAINING BUT A SINGLE NITROGEN ATOM ATTACHED TO ANY GIVEN CARBON ATOM NOT FORMING A PART OF A RING, AND REMOVING SAID SOLVENT, AND SAID STABILIZED COMPOSITION OF MATTER BEING CHARACTERIZED BY A HIGH RESISTANCE TO DETERIORATION. 